Transistor impedance converter and oscillator circuits

ABSTRACT

An impedance device adapted to represent various types of impedance which includes a two-transistor circuit equivalent to a single transistor with a common base current amplification factor greater than one and a predetermined impedance element or circuit, and circuits using such an impedance device. This impedance device represents an impedance corresponding to the impedance of the impedance element or circuit multiplied by -( Alpha 0-1) where Alpha 0 is the equivalent common base current amplification factor of the equivalent single-transistor circuit. One of the circuits using the impedance device is an oscillator which is constructed without an inductance element. Another of the circuits is an inductor having a pure inductance and which is constructed without using any inductance element.

Y i1 titted States Patent 151 smsms Miyata et a1. Feb. 1, 1972 [54]TRANSISTOR KMPEDANCE 3,153,205 /1964 Jones et a1. ..331/l CONVERTER ANDOSCILLATOR 3,167,724 1/1965 Vallese 331/115 X C S 3,384,844 5/1968Meacham ..333/80 [72] Inventors: Takeo Mliyata, Atsugi-chi; TsutomuMiura, OTHER PUBLICATIONS Kawasakl'shl both of Japan Pasupathy, ATransistor RC Oscillator Using Negative 1m- [73] Assignee; Mitsumi Eletric Com any Ltd T k pedances, Electronic Engineering, December 1966,pp. 808,

Japan 809.

[22] Filed: 1969 Primary Examiner-Roy Lake [21] App1.No.; 853,053Assistant Examiner-Siegfried l-LGrimm Attorney-Hill, Sherman, Meroni,Gross & Simpson [30] Foreign Application Priority Data [57] ABSTRACTAug. 31, Japan An impedance device adapted to represent variol'ls yp ofg 3: j impedance which includes a two-transistor circuit equivalent ug.apan ..43/62243 to a Single transistor with a common base currentamplifica tion factor greater than one and a predetermined impedance[52] US. Cl. ..331/11081R, 331/115, 3331;:i/1870BI element or circuitand circuits using Such an impedance device. This impedance devicerepresents an impedance cori g a a responding to the impedance of theimpedance element or cira c cuit multiplied by (a -1 where a is theequivalent common base current amplification factor of the equivalentsingletransistor circuit. One of the circuits using the impedance [56]References Cited device is an oscillator which is constructed without anin- UNITED STATES PATENTS ductance element. Another of the circuits isan inductor having a pure inductance and which is constructed withoutusing 2,864,062 12/1958 Schaffner .;331/ X any inductance element2,904,758 9/1959 Miranda et a1. ...333/80 T 3,144,620 8/1964 Raillard..33l/1 15 X 8Claims, 11 Drawing Figures PATENTED FEB I 1972 SHEET 1 0F2 INVENTORS 75/eo M/df/d 6/ MU/"c? TTORNEY I Tsufom PATENIED FEB 1 I972SHEET 2 BF 2 INVENTORS TRANSISTOR IMPEDANCE CONVERTER AND OSCILLATORCIRCUITS FIELD OF THE INVENTION This invention relates to an impedancedevice comprising a transistor circuit equivalent to a singlegrounded-base transistor with a current amplification factor greaterthan I, and a circuit using such an device. More particularly, thepresent invention comprises an impedance device comprising atwo-transistor circuit equivalent to a single grounded-base transistorwith a current amplification factor greater than I (unity). The circuitformed of two complementary transistors of opposite conductivity typesor the equivalent of two transistors of opposite conductivity types.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a novel impedance device including a two-transistor circuitequivalent to a single transistor with a current amplification factor(a) greater than 1.

Another object of the present invention is to provide a novel oscillatorcircuit comprising a novel impedance device including a two-transistorcircuit equivalent to a single transistor with a current amplificationfactor (a) greater than 1 and containing at least one resistor.

Still another object of the present invention is to provide a novelinductance circuit constructed of a novel impedance device including atwo-transistor circuit equivalent to a single transistor with a currentamplification factor (a) greater than I, and including a resistor and acapacitor but without using any inductance element.

Other objects, features and advantages of the present invention willbecome apparent from the following description taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a connection diagram showingan example of the circuit which can be utilized in the presentinvention;

FIGS. 2A, 2B and 2C are circuit diagrams showing the equivalent circuitsof the two-transistor circuit shown in FIG. I, respectively;

FIG. 3 is a connection diagram showing the principle of the transistorimpedance converter;

FIG. 4 is a connection diagram showing an example of the transistorimpedance converter according to an embodiment of the present invention;

FIG. 5 is a connection diagram showing an example of the oscillatorcircuit using the transistor impedance converter according to thepresent invention;

FIG. 6 is a connection diagram showing another example of the inductorusing the transistor impedance converter according to the presentinvention;

FIGS. 7 and 8 are connection diagrams showing-other examples of thetwo-transistor circuit which can be utilized in the present invention,respectively; and

FIG. 9 is a schematic diagram showing a further example of thetwo-transistor circuit which can be utilized in the present invention. I

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of thedrawings, U generally represents a two-transistor circuit equivalent toa single transistor which can be utilized in the present invention. Anexample of such circuit comprises a first PNP-transistor T1 and a secondNPN- transistor T2, with the collector of the first transistor T1connected to the base of the second transistor T2. Terminals l and 3 areconnected to the emitters of the first and second transistors T1 and T2,respectively. The base of the first transistor T1 is connected to thecollector of the second transistor T2, and a common terminal 2 is ledout of the connection point between the base of the first transistor T1and the collector of the second transistor T2.

The equivalent single transistor circuit of the invention has theforegoing arrangement. Such a circuit as shown in FIG. 4 may beconsidered as constructed by a grounded-base transistor circuit Al incascade and having a pair of input terminals corresponding to theterminals 1 and 2 connected to the first transistor T1 and having a pairof output terminals corresponding to terminals 4 and 2. Terminal 4connects to the connection point between the collector of the firsttransistor T1 and the base of the transistor T2. A groundedcollectortransistor circuit A2 has a pair of input terminals corresponding to theterminals 4 and 2 fed out of the second transistor T2. A pair of outputterminals 3 and 2, respectively, are connected to the emitter andcollector of transistor T2 as shown in FIG. 2A.

The grounded-base transistor circuit A1 may be represented as shown inFIG. 2B as an equivalent circuit in which the common base inputimpedance r of the transistor T1 is connected between the terminals Iand 2. A current source a i is connected between the terminals 4 and 2as shown by a symbol B1 in FIG. 2B, where i,, and i are the currentscaused to flow through the tenninals 1 and 4 respectively by a reversebias voltage between the base and the collector of the transistor T1 anda forward bias current between the base and the emitter, and a is thecommon base current amplification factor of the transistor T1.

The grounded-collector transistor circuit A2 may be represented by anequivalent circuit comprising a series cir cuit of the common collectoremitter impedance r of the transistor T2. A current source is connectedbetween the terminals 4 and 2 and the current source is connectedbetween the terminals 3 and 2 as shown by B2 in FIG. 28, where a, is thecommon base current amplification factor of the transistor T2. A reversebias voltage and forward bias current are imparted between the base andthe collector of the transistor T2 and between the base and the emitter,respectively.

In the equivalent circuit of FIG. 2B, the impedance is infinite asviewed from the terminals 4 and 2 toward the circuit B1, and thereforethe impedance as viewed from the terminals 3 and 2 toward the circuit B2side may also be considered infinite. Hence, the impedance r between theterminals 4 and 3 may be neglected. Thus, the current i appearing at theterminal 3 is Since the following relationship holds true r= e (2) bysubstituting equation (2) for equation (I) and rearranging the latter,the following expression is obtained:

is connected between the terminals 3 and 2. It will be seen that theterminal 1 of the equivalent single-transistor circuit shown in FIG. 1corresponds to the emitter terminal of an ordinary transistor, theterminal 2 of to the base terminal, and the terminal 3 to the collectorterminal. Therefore, the terminals 1, 2 and 3 may be referred to as theequivalent emitter, base and collector terminals, respectively. Assumingthat i /i in equation (3) is d the following equation is obtained:

a =alll a2 4 This is the equivalent common base current amplificationfactor, and r is the equivalent common base input impedance.

In the present invention, the sum of the common base currentamplification factor a, of the transistor T1 and 01 of the transistor T2is selected to be greater than 1. This is, the following relationship isestablished:

Thus, the equivalent common base current amplification factor (1represented by equation (4) is always greater than 1 As will beappreciated from the foregoing, the two transistor circuits equivalentto a single transistor circuit U shown in FIG. 1 has a common basecurrent amplification factor greater than 1. In practice, a is about 100in the case where 2SA355- and 2SC283-type transistors are employed.

In FIG. 3 the circuit U described above is used to construct animpedance device. A first terminal t1 is led out of the emitter terminal1 of the circuit U, a second terminal t2 is led out the equivalent baseterminal 2 through an impedance element or circuit P. A bias currentsource I is connected between the equivalent base terminal 2 and theequivalent emitter terminal 1 of the circuit U through the impedancecircuit P. A bias voltage source E is connected between the equivalentcollector terminal 3 and the equivalent base terminal 2 ofthe circuit Uthrough the impedance circuit P.

By connecting the negative electrode of the voltage source E to theterminal 3 of the circuit U, a current from the current source I flowstoward the terminal I of the circuit U. By suitably adjusting thevoltage and current available from the voltage source E and currentsource I, a reverse bias voltage is applied between the base and thecollector of the transistor T1 through the base emitter of thetransistor T2 and impedance circuit P. A reverse bias voltage issimilarly applied between the base and the collector of the transistorT2 through the emitter thereof and impedance circuit P. A forward biascurrent is supplied between the emitter and the base of the transistorT1 through the impedance circuit P, and a forward bias current issimilarly supplied between the base and the emitter of the transistor T2through the emitter-collector of the transistor T1 and voltage source E.Thus, the circuit U operates with an equivalent common base currentamplification factor a greater than l.

As a result, a desired impedance is obtained between the terminals 11and 12.

This impedance will beconsidered'below. Assume that the impedance of theimpedance circuit P is Z,.'Sinee the impedance between the terminals 1and 2 of the circuit U is r as described above in connection with FIG.2C, the impedance Z as viewed from between the terminals :1 and I2 is 2lI) l lhl Since a l in the present impedance device, the factor la.,)associated with Z becomes negative and therefore 2 n l lbl Byestablishing the following relationship l( n" l il l lhll the impedanceZ becomes:

It is seen that the impedance device according to the present inventionrepresents an impedance corresponding to the sum of the equivalentcommon base input impedance r of the circuit U and the impedance Z ofthe impedance circuit P with a negative factor 0f(oq,l as shown byequation (7).

Furthermore, with the impedance device of the present invention, it ispossible to obtain an impedance corresponding to the impedance Z, oftheimpedance circuit P multiplied by the negative factor of -(oz l) bysatisfying equation (8), as represented by equation (9).

It is to be particularly noted that the resent impedance devicerepresents the impedance corresponding to the impedance Z oftheimpedance circuit P multiplied by the negative factor of (a ,l) as shownin equation (9). That is,

although the impedance of the impedance circuit P is 2,, the impedanceof the present impedance device becomes equal to Z multiplied by thenegative factor of -(a -l This means that provision is made forconverting the impedance of the impedance circuit P to a negative one.Thus, in accordance with the present invention, there is provided animpedance device which is adapted to produce a negative impedancecorresponding to the impedance of the known impedance circuit Pmultiplied by the known factor of (a l Various embodiments of thepresent invention based on the principle of the impedance device of theinvention, will be described with reference to FIGS. 4 and 5.

FIG. 4 shows a first embodiment which is similar to the arrangement ofFIG. 3 except that the impedance circuit P is formed ofa parallelcircuit CR ofa resistance element R2 and capacitance element CC. Thoseparts of FIG. 4 corresponding to those of FIG. 3 are indicated by likereferences, and a detailed description will be omitted. This embodimentis adapted to produce the following effect: Assuming that the resistanceof the resistance element R2 is r that the capacitance of thecapacitance element CC is C and that the impedance of the parallelcircuit CR is 2, this impedance is given by (wCcr l then the followingequation holds;

Z'=l/jwCc Thus, the impedance Z is given by 2 0 lbr im n ([3) Byestablishing the following relationship |(oz l Z'l l r the impedance Zbecomes as follows:

Z =(a 1)Z.'

It is to be particularly noted that this embodiment represents animpedance equal to the sum of a negative resistance -(a lr and animpedance based on an inductance of (a l )C rf. That is, although theparallel circuit CR of the resistance element R2 and capacitance elementCC is connected to the equivalent base terminal of circuit U, animpedance based on the sum of a negative resistance corresponding to theresistance of the resistance element R2 multiplied by a negative factorof (a l) and an impedance based on an inductance corresponding to theproduct of the square of the resistance of the resistance element R2 andcapacitance of the capacitance element multiplied by a positive factorof (oar-l) is obtained. This means that in case it is desired toeliminate the effect of a residual resistance in a certain circuit inwhich an inductor is to be connected, this can be automatically achievedby connecting this circuit across the terminals t1 and :2 of FIG. 45.Furthermore, it is possible to construct an oscillator by connectinganother capacitance element between the terminals 11 and t2 and apredetermined load between the equivalent collector terminal 3 of thecircuit U and the terminal t2. Also, by connecting a resistance elementhaving a resistance substantially equal to (cry-1T in series with theterminal :1, this embodiment is the equivalent of an inductorrepresenting a pure inductance even though no inductance is used and thecircuit is constructed from resistance and capacitance elements.

It is to be noted that this embodiment represents an impedance based ona negative capacitance of e it iqill.

as seen from equation (15). That is, although the*eapacitance element isconnected to the base of the circuit U, this embodiment represents animpedance based on a negative capacitance corresponding to thecapacitance of the capacitance element multiplied by the reciprocal of anegative factor (a l This means that in case it is desired to eliminatethe effect of a residual impedance based on a residual capacitancepresent in a certain circuit, such residual impedance can beautomatically cancelled or compensated for by utilizing the circuitshown in FIG. 4.

Referring to FIG. 5 there is shown an example of the oscillator of thepresent invention which is constructed by the use of the impedancedevice described above in connection with FIG. 4. The embodiment shownin FIG. 5 is similar to the arrangement of FIG. 4 except that a load Lis connected between the terminals 3 and t2 and a capacitance element CFis connected between the terminals t1 and r2. Therefore, parts of FIG. 5corresponding to those of FIG. 4 are indicated by like reference symbolsand their description will be omitted. It is assumed that the impedanceof the parallel circuit CR is Z as described above in connection withFIG. 4 and impedance z is given by equation In this embodiment, thevalues r and C of the resistance element R2 and capacitance element CCare selected so as to meet equation (11) to obtain equation 12).

With the foregoing arrangement, the impedance between the terminals t1and I2 is given'by equation (13) in the case where the capacitanceelement CF is not connected between the terminals 11 and :2. Further,equation (13) is changed to equation (15) by satisfying the relationshiprepresented by equation (14). Therefore, the impedance between theterminals t1 and t2 is the sum of a negative resistance R and animpedance based on an inductance which is given by L=(a l )C rf (16) Theabsolute value of the negative resistance -R' is given by 0 zm (m in thecase where equation I3) is applied and by R'=(u l )r (17) in the casewhere equation 15) is applied.

The arrangement according to the present invention wherein thecapacitance element CF is connected between the terminals t1 and t2 asshown in FIG 5 makes it possible to produce oscillation at a frequencywhich depends upon the inductance L or (om-UG-m in equation (16) and thecapacitance C, of the capacitance element CF. The oscillation output isavailable across the load LO.

The embodiment shown in FIG. 5 discloses an oscillator having asimplified arrangement. It is to be particularly noted here thatalthough an inductor is'usually required by a conventional oscillator,an inductor in the oscillator is not needed in the present invention.Thus, the oscillator circuit according to the present invention can beconstructed in the form of an integrated circuit.

In an actual example of the circuit shown in FIG. 5, the transistors T1and T2 were type 2SA2 l0 and 2SC283 transistors, respectively; thecapacitance C of the capacitance element C C was pf.; the resistance r,of the resistance element R2 was 1 K0; the load LO was a resistor of100.0; the voltage of the voltage source E was 6 v.; and the currentsource I was a circuit in which a resistor of 30 K0 was connected inseries with a DC power source. By supplying a current of 1 ma. to theterminal 1, there was obtained a sinusoidal oscillation output of 1.5 v.(peak-to-peak) at 1 MHz.

A description will be given of an example of the inductor embodying thepresent invention which is constructed by using the'impedance device ofFIG. 4 with reference to FIG. 6.

The embodiment of FIG. 6 is similar to that of FIG. 4 except that aresistor R3 is inserted in the line between the terminals :1 and 1.Therefore, parts of FIG. 6 corresponding to those of FIG. 4 areindicated by the same reference symbols and description will be omitted.

The impedance Z of the parallel circuit CR is given by the equation (10) In this embodiment, the values r and C, of the resistance element R2and capacitance element CC are selectedso as to meet equation (ll).Thus, equation (12) is obtained. 3

In the foregoing arrangement, the impedance between terminals t1 and :2is given by equation 13) where the resistance element R3 is absent or isshort circuited. Further, equation l3) is changed to equation 15) byestablishing the relationship represented by equation l4).

Thus, with the arrangement of FIG. 6 wherein the resistance element R3is connected between the terminals t1 and t2 and, satisfying theconditions of equations (1 l) and (14), the impedance between theterminals I1 and 12 is given by 2 o 2+j o c 2 3 where r;, is theresistance value of the resistance element R3. Therefore, by selectingthe resistance value r; to meet the following relationship s= i o 2|(l9) equation 18) can be rewritten as follows:

From the foregoing, it will be seen that the arrangement of FIG. 6serves as an inductive circuit having a pure inductance between theterminals t1 and t2 which is represented by The embodiment of FIG. 6,provides an inductor having a pure inductance but including onlycapacitive and resistive elementsvTherefore, such inductor can be easilyconstructed in the from of an integrated circuit.

In the circuit U described in FIG. 1, the base of the PNP- transistor T1is connected to the collector of the NPN- transistor T2, and thetenninal 3 was led out of the emitter of the transistor T2. However, itis also possible that the base of the transistor T1 be connected to theemitter of the transistor T2 and that the terminal 3 be led out of thecollector of the transistor T2, as shown in FIG. 7. Furthennore, it isalso possible that the emitter of the transistor T1 be connected to thebase of transistor T2 and that the terminal 1 be led out of thecollector of the transistor T1, as shown in FIG. 8. With sucharrangements equivalent common base current amplification factora of thecircuit U becomes greater than I as in the case of FIG. l. A transistorgenerally has interchangeability between the emitter and the collector.In the arrangements of FIGS. 7 and 8, however, the equivalent commoncurrent amplification factor becomes smaller than in the case of FIG. 1.For example, when type 2SA355 and 2SC283 transistors are used for thetransistors T1 and T2 respectively, a becomes about 2.5 in the case ofFIG. 7 and about 20 in the case of FIG. 8. The transistors T1 and T2have been described as being of the PNP-and NPN-types respectively.However, the conductivity types of these transistors may be reversed.That is, the transistors TI and T2 may be of the NPN- and PNP-typesrespectively, and it is possible to produce the same effect as describedabove, by reversing the polarities of the voltage source and currentsource, as will be readily apparent to those skilled in the art.

The transistor circuit with an equivalent common base currentamplification factor greater than 1 was constructed by the use of twotransistors T1 and T2. For example, it is also possible to construct thetransistor circuit by taking the equivalent emitter terminal 1 out ofthe first P- (or N-) type layer of a PNP (or NPNP type semiconductordevice and the equivalent base terminal 2 out of the immediatelyadjacent N- (or P-) type layer and the equivalent collector terminal 3out of the last N- (or P-) type layer as shown in FIG. 9.

Although the present invention has been illustrated and described withrespect to particular examples, various modifications and changes willbecome possible without departing from the spirit and scope of thepresent invention. It is to be understood that such modifications andchanges also constitute part of the present invention.

What is claimed is:

l. A transistorized circuit comprising a pair of transistors of oppositeconductivity types,

the base electrode of the first transistor connected to the collector ofthe second transistor,

a collector of the first transistor connected to the base of the secondtransistor,

a first resistor,

a first capacitor connected in parallel with said first resistor and oneside of the parallel combination connected to the base of said firsttransistor,

a voltage source connected to the other side of said parallelcombination and to the emitter of said second transistor, and

a current source connected between the emitter of said first transistorand the other side of said parallel combination.

2. A transistorized circuit according to claim 1 comprising a secondcapacitor connected in parallel with said current source.

3. A transistorized circuit according to claim 2 comprising a secondresistor connected between said voltage source and said emitter of saidsecond transistor.

4. A transistorized circuit according to claim 2 comprising a pair ofinput terminals with one connected to the junction point between saidvoltage source and said parallel combination, and a second resistorconnected between said second input terminal and said emitter of saidfirst transistor.

5, A transistor impedance converter comprising a twotransistor circuitconsisting of first and second transistors of opposite types ofconductivity equivalent to a single transistor having a common basecurrent amplification factor a greater than 1, an impedance circuitconstituted of a parallel circuit of a resistance element having aresistance r and a capacitance element having a capacitance C one end ofsaid impedance circuit being connected to the equivalent base terminalof said two-transistor circuit, a first external terminal connected tothe equivalent emitter terminal of said two-transistor circuit, a secondexternal terminal connected to the other end of said impedance circuit,and means for imparting an operating power source to said two-transistorcircuit, said resistance r and said capacitance C being so selected asto meet a relationship of (wC,r l, to being an operational angularfrequency, thereby obtaining an impedance substantially equal to the sumof a negative resistance (a,,l) r and an impedance based on aninductance (a -l )C r between said first and second terminals withoutusing any inductor.

6. A transistor impedance converter comprising a twotransistor circuitconsisting of first and second transistors of opposite types ofconductivity equivalent to a single transistor having a common basecurrent amplification factor 01 greater than I, an impedance circuitconstituted ofa parallel circuit of a resistance element having aresistance r and a capacitance element having a capacitance C,, one endof said impedance circuit being connected with the equivalent baseterminal of said two-transistor circuit, a first external terminalconnected with the equivalent emitter terminal of said two-transistorcircuit, a second external terminal connected with the other end of saidimpedance circuit, and means for imparting an operating power source tosaid two-transistor circuit, said resistance r and said capacitance Cbeing so selected as to meet a relationship of (mC r l, on being anoperational angular frequency, thereby obtaining an impedance based on anegative capacitance between said first nd second terminals.

7. An oscillator circuit comprising the transistor impedance converterset forth in claim 6, and a capacitor having a capacitance C connectedbetween said first nd second external terminals, thereby producingoscillation at a frequency represented substantially by without usingany inductor.

8. A transistor impedance converter comprising a twotransistor circuitconsisting of first and second transistors of opposite types ofconductivity equivalent to a single transistor having a common basecurrent amplification factor a greater than I, an impedance circuitcomprising a parallel circuit of a resistance element having aresistance r and a capacitance element having a capacitance C one end ofsaid impedance circuit being connected to the equivalent base terminalof said two-transistor circuit, a first external terminal connected withthe equivalent emitter terminal of said two-transistor circuit, a secondexternal terminal connected to the other end of said impedance circuit,means for imparting an operating power source to said two transistorcircuit, and a resistor having a resistance r inserted in the linebetween said first external terminal and said equivalent emitterterminal of said twotransistor circuit, said resistance r; and saidcapacitance C being so selected as to meet a relationship of (mC r 1, tobeing an operational angular frequency, and said resistance r, of saidresistor being so selected substantially as to meet a relationship ofrHa l )r thereby obtaining an impedance based on an inductance (m -DC;between said first and second external terminals without using anyinductor.

1. A transistorized circuit comprising a pair of transistors of oppositeconductivity types, the base electrode of the first transistor connectedto the collector of the second transistor, a collector of the firsttransistor connected to the base of the second transistor, a firstresistor, a first capacitor connected in parallel with said firstresistor and one side of the parallel combination connected to the baseof said first transistor, a voltage source connected to the other sideof said parallel combination and to the emitter of said secondtransistor, and a current source connected between the emitter of saidfirst transistor and the other side of said parallel combination.
 2. Atransistorized circuit according to claim 1 comprising a secondcapacitor connected in parallel with said current source.
 3. Atransistorized circuit according to claim 2 comprising a second resistorconnected between said voltage source and said emitter of said secondtransistor.
 4. A transistorized circuit according to claim 2 comprisinga pair of input terminals with one connected to the junction pointbetween said voltage source and said parallel combination, and a secondresistor connected between said second input terminal and said emitterof said first transistor.
 5. A transistor impedance converter comprisinga two-transistor circuit consisting of first and second transistors ofopposite types of conductivity equivalent to a single transistor havinga common base current amplification factor Alpha 0 greater than 1, animpedance circuit constituted of a parallel circuit of a resistanceelement having a resistance r2 and a capacitance element having acapacitance Cc, one end of said impedance circuit being connected to theequivalent base terminal of said two-transistor circuit, a firstexternal terminal connected to the equivalent emitter terminal of saidtwo-transistor circuit, a second external terminal connected to theother end of said impedance circuit, and means for imparting anoperating power source to said two-transistor circuit, said resistancer2 and said capacitance Cc being so selected as to meet a relationshipof ( omega Ccr2)2<<1, omega being an operational angular frequency,thereby obtaining an impedance substantially equal to the sum of anegative resistance -( Alpha O-1) r2 and an impedance based on aninductance ( Alpha 0-1)Ccr22 between said first and second terminalswithout using any inductor.
 6. A transistor impedance convertercomprising a two-transistor circuit consisting of first and secondtransistors of opposite types of conductivity equivalent to a singletransistor having a common base current amplification factor Alpha 0greater than 1, an impedance circuit constituted of a parallel circuitof a resistance element having a resistance r2 and a capacitance elementhaving a capacitance Cc, one end of said impedance circuit beingconnected with the equivalent base terminal of said two-transistorcircuit, a first external terminal connected with the equivalent emitterterminal of said two-transistor circuit, a second external terminalconnected with the other end of said impedance circuit, and means forimparting an operating power source to said two-transistor circuit, saidresistance r2 and said capacitance Cc being so selected as to meet arelationship of ( omega Ccr2)2<<1, omega being an operational angularfrequency, thereby obtaining an impedance based on a negativecapacitance between said first nd second terminals.
 7. An oscillatorcircuit comprising the transistor impedance converter set forth in claim6, and a capacitor having a capacitance Cf connected between said firstnd second external terminals, thereby producing oscillation at afrequency represented substAntially by without using any inductor.
 8. Atransistor impedance converter comprising a two-transistor circuitconsisting of first and second transistors of opposite types ofconductivity equivalent to a single transistor having a common basecurrent amplification factor Alpha 0 greater than 1, an impedancecircuit comprising a parallel circuit of a resistance element having aresistance r2 and a capacitance element having a capacitance Cc, one endof said impedance circuit being connected to the equivalent baseterminal of said two-transistor circuit, a first external terminalconnected with the equivalent emitter terminal of said two-transistorcircuit, a second external terminal connected to the other end of saidimpedance circuit, means for imparting an operating power source to saidtwo transistor circuit, and a resistor having a resistance r3 insertedin the line between said first external terminal and said equivalentemitter terminal of said two-transistor circuit, said resistance r2 andsaid capacitance Cc being so selected as to meet a relationship of (omega Ccr2)2<<1, omega being an operational angular frequency, and saidresistance r3 of said resistor being so selected substantially as tomeet a relationship of r3 ( Alpha 0-1)r2, thereby obtaining an impedancebased on an inductance ( Alpha 0-1)Ccr22 between said first and secondexternal terminals without using any inductor.